A vehicle assembling line assembles a vehicle by attaching several kinds of parts to a vehicle body while the vehicle body is transferred by a hanger or by a pallet carried along a conveying line. Hereupon, a wiring for an electric system, interior parts such as an instrumental panel or seat, parts for underbody such as engine or tire, and exterior parts such as mirror or wiper are attached to the vehicle body.
Of these, wiring for electric system and interior parts such as the instrument panel are manually attached by workers to the vehicle body loaded onto the pallet circulating through a line-arrangement or a flat loop-arrangement conveying line. Especially, the assembling line installed as a flat loop-arrangement can be widely used because the constitution of the conveying line can be simplified and utilization efficiency of a factory site can be improved.
As a conventional example of the assembling line installed as a flat loop-arrangement and the pallet conveying mechanism used for this assembling line, some of these are disclosed in Japanese Unexamined Patent Publication Sho. 58-22633 or Japanese Examined Patent Publication Sho. 61-33743.
The assembling line according to Japanese Unexamined Patent publication Sho. 58-22633 is comprised of a pair of conveying lines and a pair of traverse lines connected to each other. Rails established along each line and a moving mechanism to move the pallet along the rails are used for the pallet conveying mechanism.
Furthermore, the assembling line according to Japanese Examined Patent publication Sho. 61-33743 has a pair of conveying lines and a traverse line connected to each other. Additionally, the pallet conveying mechanism used in this assembling line is comprised of a rack gear provided along the traverse line and a traversor equipped with the pallet to move from one edge to the other edge of a traverse line. Moreover, the traversor includes a drive mechanism and a tuning table engaging with a rack gear to turn the pallet.
According to this pallet conveying mechanism, the pallet is loaded onto the traverser to be transferred from one end portion to the other end portion of the traverse line, at the same time as it is turned 180° around by the turning table.
However, this assembling line has a problem such that the pallet conveying mechanism is complicated in structure. More specifically, the pallet conveying mechanism according to Japanese Unexamined Patent Publication Sho. 58-22633 has a mechanism to slide the pallet along rails. Therefore, the pallet is required to have the mechanism capable of moving in not only lengthwise direction but also breadthwise direction and means for switching the moving direction. Consequently, the pallet conveying mechanism is complicated in structure.
On the other hand, the pallet conveying mechanism according to Japanese Examined Patent Publication No. 61-33743 has a mechanism to turn the pallet while conveying the pallet. Therefore, the mechanism for conveying the pallet is complicated. Meanwhile, since the following pallet cannot be conveyed until the traversor is returned to the original position after conveying the pallet, it takes much time to convey the pallet on the traverse line.